divx 5.0.2 decoder quality settings

[personal]

hello
can someone explain what do the quality settings in the divx 5.0.2 decoder properties do? i looked around in divx.com, the forums, i even clicked the big help button in the help page of decoder properties :)
(does this help button really work?)
i found out with trial and error that 'overlay extended mode' frees some cpu, hey, i can even play divx on my old pII 350/128mb ram/tnt2 but what about the other options?
cya
personal
PS am i off topic here? :)

[FDISK]

Smooth Playback: Reduces CPU usage and frame stuttering during playback, making the video more smooth.

YUV Extended Mode: Playback in YUV color mode. It decreases CPU usage, and may increase image quality slightly.

Overlay Extended Mode: Uses your videocard's hardware overlay support. If your videocard supports this, it will increase performance and may increase image quality slightly.

Double Buffering: A trick to prevent stuttering and dropped frames. It may cause playback issues (jerkiness) so disable it if you have problems.

[mustaneekeri]

U didn't look hard enough: http://www.divx.com/divx/divx_win_versions.php

FDISK, i understood that Smooth Playback does reduce stuttering but it does not reduce CPU usage, instead turning it off reduces CPU usage and allows video to be played with lower end CPUs.

[timeToy]

Smooth playback is for B frames clips only, it has no effets on clips without B frames.
When it's on it helps reducing the B frames CPU overhead on low end CPU (under 700Mhz).